Suicide is the third leading cause of death in youth ages 10-24, and the consequences of suicidal ideation and attempts impact tens of thousands more. In 1999, the Surgeon General called for a national plan to increase research, prevention, and intervention efforts. One goal was improving self-report measures to assess suicidality in youth. Two important aspects of that work include studies to further our understanding of the experience of suicide risk constructs in youth, and research on the validity of self-report instruments to measure those constructs. However, developing valid self-report measures for use with children is difficult due to the cognitive developmental differences between youth and researchers. Those differences can result in youth interpreting items differently than intended, introducing error into those measures. Applying cognitive methods to the development of self-report instruments for children and adolescents presents an emerging approach to advance the validity of those instruments. Cognitive methods are a family of instrument development methods that involve collecting data directly from respondents about how they think about they experience the targeted constructs and how they cognitively process self-report items measuring those constructs. That data is then used to develop instruments informed by more valid conceptualizations of the constructs leading to self-report items that are more accurately interpreted by respondents and therefore more valid measures. This proposed study will apply two cognitive methods to advance the validity of adolescent suicidality instruments. The first method is construct probe interviews, which gather data from respondents about how they experience constructs that are the target of self-report instruments. The second method is cognitive pretesting, which involves interviewing respondents as they read and respond to self-report items. The findings from these methods will inform our understanding of suicidality in adolescents and the development of more valid suicidality assessment instruments. [unreadable] [unreadable] [unreadable] [unreadable]